Envelope inserting apparatus are used in many instances where the volume of envelopes to be filled makes manual insertion impractical. Machines for inserting planar articles into envelopes frequently are used by high volume mailers such as banks, insurance companies, government agencies and commercial mailing establishments.
The prior art includes many types of envelope inserting machines. One type of prior art envelope inserter uses a plurality of vacuum operated suction devices in combination with mechanical devices which advance the envelopes and inserts through the system. More particularly, this type of prior art envelope inserter employs a vacuum to feed inserts and envelopes into the apparatus. The inserts and envelopes then are mechanically advanced on separate conveyors. At an appropriate location in this prior art inserter, the envelope and insert conveyors are stopped, and a second vacuum apparatus is employed to open the envelope sufficiently to enable the envelope to accept the insert. While the mechanical conveyors are stopped, the insert is pushed in a direction substantially perpendicular to its previous direction of movement and into the envelope that has been opened by the vacuum apparatus. This prior art apparatus then mechanically conveys the envelope, with the insert included, to other locations where the envelope is sealed, posted, and sorted for distribution.
The vacuum operated prior art envelope inserting machine has several disadvantages. First, the vacuum system, which is central to this prior art inserter, sucks in a substantial volume of dust and small paper particles. Consequently, this prior art apparatus is subject to frequent malfunctions. Specifically, the machine frequently feeds either too few or too many inserts onto the mechanical conveyor. In other instances, the vacuum fails to properly open the envelope thereby preventing complete insertion of the insert. In view of these problems, prior art machines of this type require frequent cleaning and maintenance which is costly and which results in substantial down time. Second, the mechanical conveyors in the prior art vacuum operated inserters are abruptly stopped and started each time an insert is placed in an envelope. This abrupt and frequent lurching places a tremendous strain on many parts of the apparatus, and in turn, eventually causes those parts to fail. Additionally, the periodic stopping and starting substantially reduces the maximum output of this prior art apparatus. For example, in most operating environments, prior art machines of this type cannot realistically be operated to insert more than 7,000 envelopes per hour. Attempts to increase the speed at which the insert approaches the envelope have led to additional problems because the leading edge of the accelerating insert frequently lifts out of the plane of the remainder of the insert and slides over the top of the envelope opening.
Other prior art inserting apparatus have been developed which rely upon friction to feed inserts and envelopes into the apparatus and to open the envelopes wide enough to accept the inserts. Although this latter type of prior art inserter overcomes the previously described problems associated with vacuum systems, the mechanical components that replace the vacuum system require significantly more moving parts, and therefore have a high probability of mechanical failure. Additionally, the latter type of prior art inserter requires a distinct stopping and starting step each time an insert is placed in an envelope. As explained above, frequent stops and starts contribute to stress related mechanical failures and significantly affect the maximum operating speed of the inserter.
In view of the above, it is an object of the subject invention to provide an automatic inserting apparatus for envelopes that operate with a minimum number of moving parts.
It is another object of the subject invention to provide an automatic inserting apparatus for envelopes which does not rely upon a vacuum system.
It is an additional object of the subject invention to provide an automatic inserting apparatus for envelopes that enables the continuous and simultaneous movement of both the envelopes and the inserts.
It is still another object of the subject invention to provide an automatic inserting apparatus for envelopes that enables inserts to be placed in envelopes at a faster rate than existing inserters.